Clinical studies related to cardiac pacing have shown that an optimal atrio-ventricular pacing delay (e.g., AV delay or PV delay) and/or an optimal interventricular pacing delay (e.g., VV delay) can improve cardiac performance. However, such optimal delays depend on a variety of factors that may vary over time. Thus, what is “optimal” may vary over time. An optimization of AV/PV pacing delay and/or VV pacing delay may be performed at implantation and sometimes, a re-optimization may be performed during a follow-up consultation. While such optimizations are beneficial, the benefits may not last due to changes in various factors related to device and/or cardiac function.
The following patents and patent applications set forth various systems and methods for allowing a pacemaker, implantable cardioverter-defibrillator (ICD) or other cardiac rhythm management (CRM) device to determine and/or adjust AV/PV/VV pacing delays so as to help maintain the pacing delays at optimal values: U.S. patent application Ser. No. 10/703,070, filed Nov. 5, 2003, entitled “Methods for Ventricular Pacing”; U.S. patent application Ser. No. 10/974,123, filed Oct. 26, 2004; U.S. patent application Ser. No. 10/986,273, filed Nov. 10, 2004; U.S. patent application Ser. No. 10/980,140, filed Nov. 1, 2004; U.S. patent application Ser. No. 11/129,540, filed May 13, 2005; U.S. patent application Ser. No. 11/952,743, filed Dec. 7, 2007. See, also, U.S. patent application Ser. No. 12/328,605, filed Dec. 4, 2008, entitled “Systems and Methods for Controlling Ventricular Pacing in Patients with Long Intra-Atrial Conduction Delays” and U.S. patent application Ser. No. 12/132,563, filed Jun. 3, 2008, entitled “Systems and Methods for determining Intra-Atrial Conduction Delays using Multi-Pole Left Ventricular Pacing/Sensing Leads.” See, also, U.S. Pat. No. 7,248,925, to Bruhns et al., entitled “System and Method for Determining Optimal Atrioventricular Delay based on Intrinsic Conduction Delays.” At least some of the techniques are implemented within the QuickOpt™ systems of St. Jude Medical.
In particular, techniques are set forth within at least some of these patent documents for exploiting various inter-atrial and interventricular conduction delays to determine preferred or optimal AV/PV/VV pacing delays. Techniques are also set forth for exploiting the VV delays to determine which ventricles should be paced—the left ventricle (LV), the right ventricle (RV), both ventricles, or neither, and in which order. In at least some examples, the implanted device (or an external programming device in communication with the implanted device) performs a series of tests to determine intrinsic AV/PV and VV conduction delays from which preferred pacing delays are determined. In particular, an “A sense” test is performed to detect intrinsic intra-atrial delays from which preferred AV/PV pacing delays are determined. A “V sense” test is performed to detect intrinsic ventricular events from which an intrinsic interventricular conduction delay (Δ) is determined. An “RV pace” test and a separate “LV pace” test are performed to detect paced interventricular conduction delays (IVCD_RL and IVCD_LR, respectively) from which an interventricular correction term (ε) is determined. The optimal VV delay for use in biventricular pacing is then set based on Δ and ε.
For implantable systems equipped with multi-pole LV leads (i.e. leads with a set of LV electrodes for pacing/sensing at different sites on or within the LV), special techniques may be employed to perform the various tests to determine values for Δ and ε for use in determining the VV delays for use with the various LV electrodes. In particular, see U.S. patent application Ser. No. 12/507,646, of Min, filed Jul. 22, 2009, entitled “Systems and Methods for Optimizing Ventricular Pacing Delays for use with Multi-Pole Leads” which sets forth improved techniques for determining VV delays for use with multi-pole LV leads. See, also, U.S. patent application Ser. No. 12/507,679, of Min, filed Jul. 22, 2009, entitled “Systems and Methods for Optimizing Ventricular Pacing Delays during Atrial Fibrillation”, which describes special techniques for performing V sense, RV pace and LV pace tests during atrial fibrillation (AF.) These last two documents are incorporated by reference herein in their entirety.
When employing a multi-pole LV lead, it is also useful to identify an optimal pair of LV/RV electrodes for use in delivering biventricular pacing (i.e. to identify an optimal pacing site) and it is to this end that aspects of the invention are directed.